Leaf Glossiness Research Articles

An increased wax load on the leaves of goji plants (Lycium barbarum) results in increased resistance to powdery mildew

Abstract Background Goji (Lycium barbarum) is an important economic crop that is widely cultivated in Northwest China and is known as superfood. Goji plants are often affected by powdery mildew (Arthrocladiella mougeotii) in the field, resulting in considerable reduction in production and serious economic losses. The long-term reliance on agricultural chemicals to control powdery mildew not only leads to environmental pollution, but also causes excessive residues to accumulate in fruits, endangering human health. The plant epicuticular wax is the first physical barrier between land plants and the atmospheric environment, and plays an important role in the interactions of plants with pathogenic microorganisms. However, the relationship between epicuticular wax and powdery mildew resistance in goji plants is not well understood. Results The leaf epicuticular wax crystals of ‘Ningqi I’ goji were dense and small, and the wax load was 121.74 μg/cm2, which was 3.36 times greater than that of ‘Huangguo’ goji. The ratio of alcohol components in ‘Ningqi I’ goji was 121.18% greater than that in ‘Huangguo’ goji. The incidence rate and disease index of ‘Ningqi I’ goji inoculated with powdery mildew were significantly lower than those inoculated ‘Huangguo’ goji, showing high resistance and moderate susceptibility, respectively. After mechanical wax removal, the disease indices of the two goji varieties increased significantly, indicating extreme susceptibility. Seventeen differential expression genes showing significantly greater expression in ‘Ningqi’ goji leaves than in ‘Huangguo’ goji leaves were enriched in genes involved in fatty acid elongation and the wax biosynthesis pathway. The FAR activity and relative expression levels of LbaFAR and LbaWSD1 in ‘Ningqi I’ goji were significantly greater than those in ‘Huangguo’ goji. The relative expression levels of these genes significantly increased in the overexpression tobacco lines FAR-OE and WSD1-OE, and the wax load were augmented by 46.10% and 22.23%, respectively. Conclusions The increased expression of the LbaFAR and LbaWSD1 genes in ‘Ningqi I’ leaves led to increased FAR and WSD1 activity, increasing the wax load and alcohol content of the epicuticular of leaves, and improving leaf glossiness, resulting in strengthened resistance to powdery mildew. Therefore, the production of leaf epicuticular wax mediated by the LbaFAR and LbaWSD1 genes could be the main reason for the difference in powdery mildew resistance between the two goji varieties, which can provide a theoretical basis for the selection of resistant varieties to control goji powdery mildew. Graphical Abstract

Prevalence, Cultural And Morphological Characterization Of Fusarium Verticillioides Associated With Ear Rot Of Maize

Sorghum shoot fly, Atherigona soccata (Rondani) is an important pest of sorghum distributed in almost all sorghum growing areas of India, attacking the crop at the seedling stage wherein the absence of appropriate management measures may result in heavy yield loss and host plant resistance is a major component in managing this pest. Utilization of resistance as a control strategy has very much practical relevance and hence identification of resistant sources for shootfly through morphological and physicochemical characteristics was carried out in pre-release sorghum genotypes of Tamil Nadu Agricultural University. Leaf glossiness, trichome density, trichome length, trichome width, and seedling vigor were associated with resistance and had a major bearing on the expression of resistance to shoot fly. Among the genotypes tested, TNS 671 and TNS 665 showed better performance in terms of dead heart, percentage of plants with eggs, and recovery resistance compared to others which were then subjected to biochemical estimation and GCMS analysis. Leaf biochemical characters viz., total phenol, cellulose, total amino acids, silica, tannin, and lignin were found to be negatively correlated and total sugar positively correlated with resistance. GC-MSanalysis of the sorghum genotypes revealedthe presence of compounds, viz., carboxylic acids, heptadecene, and hentriacontane only in the resistant entry, IS18551. An interesting finding of this study was the presence of hentriacontanein resistant cultivar, IS18551 which is reported to have kairomonal activity. The characters associated with resistance or susceptibility can be used in further resistant breeding programmes.

Morphological And Biochemical Resistance In Sorghum Genotypes Against Sorghum Shoot Fly, Atherigona Soccata (Rondani) (Muscidae: Diptera)

Sorghum shoot fly, Atherigona soccata (Rondani) is an important pest of sorghum distributed in almost all sorghum growing areas of India, attacking the crop at the seedling stage wherein the absence of appropriate management measures may result in heavy yield loss and host plant resistance is a major component in managing this pest. Utilization of resistance as a control strategy has very much practical relevance and hence identification of resistant sources for shootfly through morphological and physicochemical characteristics was carried out in pre-release sorghum genotypes of Tamil Nadu Agricultural University. Leaf glossiness, trichome density, trichome length, trichome width, and seedling vigor were associated with resistance and had a major bearing on the expression of resistance to shoot fly. Among the genotypes tested, TNS 671 and TNS 665 showed better performance in terms of dead heart, percentage of plants with eggs, and recovery resistance compared to others which were then subjected to biochemical estimation and GCMS analysis. Leaf biochemical characters viz., total phenol, cellulose, total amino acids, silica, tannin, and lignin were found to be negatively correlated and total sugar positively correlated with resistance. GC-MSanalysis of the sorghum genotypes revealedthe presence of compounds, viz., carboxylic acids, heptadecene, and hentriacontane only in the resistant entry, IS18551. An interesting finding of this study was the presence of hentriacontanein resistant cultivar, IS18551 which is reported to have kairomonal activity. The characters associated with resistance or susceptibility can be used in further resistant breeding programmes.

Comparison of Shoot Fly Resistance QTLs in Sorghum Introgression Lines Using SNP Genotyping

Shoot fly is a major pest in sorghum that causes significant annual yield loss. Use of pesticide to control this pest is an expensive and environmentally unsafe approach. Present study investigated the host plant resistance mechanism to develop shoot fly resistance (SFR) lines through transfer of shoot fly resistance QTLs (glossiness, trichome density, ovipositional non-preference) using SSR marker assisted backcrossing. Genomic regions for SFR showed four QTLs on SBI 01, SBI 07, SBI 05 and SBI 10 contributing up to 11.5%, 18.3%, 14% and 14.7% phenotypic variation. But QTLs on SBI 05 and SBI 10 for glossiness and trichome density are the major QTLs for which 10 SNPs have been designed. In earlier studies, three QTL regions associated with shoot fly resistance were successfully introgressed into elite cultivar SPV 1411 (Parbhani Moti) and a B line ICSB29004 using donors viz. J2658 (SBI01), J2614 (SBI10), and J2714 (SBI07) (which are derivatives of BTx 623). Phenotyping of introgression lines (ILs) led to the identification of resistant lines for each QTL region present on chromosome SBI-01, SBI-07 and SBI-10. Hence, in this study we have analysed the above developed ILs using single-nucleotide polymorphism (SNP) markers tightly linked to shoot fly resistant QTLs. The results showed that introgression lines with QTL present on chromosome SBI-10 were segregating for favorable alleles for leaf glossiness and for trichome density in homozygous condition. Other introgression lines with QTLs on chromosome SBI-01 and SBI-07 for component traits - oviposition non-preference, seedling vigor are segregated for glossiness trait also thus showing the transfer of non-targeted region, which in this case proved beneficial for SFR. This study showed that these SNPs can be used to analyze introgression lines and can be used as genomic markers for early generation selection of shoot fly resistance lines.

Morphological traits of wheat (Triticum aestivum L.) associated with resistance to shoot fly, Atherigona approximata Malloch

• Shoot fly caused 26 % of crop damage in wheat. • UAS BW-12417 and UAS BW-11110 genotypes recorded least oviposition and dead heart. • Correlation between crop damage and biophysical factors was significant. • All the biophysical parameters are independent and affect the crop damage in wheat. Shoot flies ( Atherigona spp.) are the members of muscidae family which have got economic importance as pest of several crops of Gramineae family mostly cereals and millets. One of the most effective management strategies for controlling shoot fly is the use of resistant wheat cultivars carrying specific resistant traits. Among thirty wheat genotypes screened at the University of Agricultural Sciences, Dharwad-Karnataka (India), two advanced germplasms UAS BW-12417 and UAS BW-11110 recorded least oviposition and dead heart due to shoot fly and found to be less preferred by Atherigona approximata Malloch. The morphological traits of different wheat genotypes revealed a significant negative correlation of shoot fly oviposition and dead heart with leaf length, leaf length to breadth ratio, seedling height, average seedling growth rate, seedling vigour, leaf glossiness and trichome density of wheat leaves, which indicated the enhanced shoot fly infestation as decrease in the values of above-mentioned morphological traits. Meanwhile, increase in leaf breadth and leaf area of wheat genotype aggrandised the oviposition and dead heart damage by shoot fly. Under the changing climate where, the minor insect pests attaining major pest status, the present investigation would pave way for breeders to tailor future breeding programmes to evolve shoot fly resistant hybrids with high yielding traits.

Susceptibility of Rose Varieties Against Pests in Relation to Plant Morphological Characters Under Open Field Condition

Rose is attacked by thrips, <i>Frankliniella schultzei</i> (Pergande), <i>Scirtothrips dorsalis</i> Hood; aphid, <i>Macrosiphum rosae</i> (Linnaeus); whitefly, <i>Trialeurodes vaporariorum</i> (Westwood); mealybug, <i>Planococcus citri</i> (Risso); foliage feeders and bud borers, <i>Helicoverpa armigera</i> (Hubner); <i>Spodoptera litura</i> (Fabricius) and mite, <i>Tetranychus urticae</i> Koch. As great deal of variation of pest attack to rose varieties exists, role of plant morphological characters in inducing plant resistance need investigation. Rose varieties Barbone rose, cabbage rose, Chinese rose and Gladiator were screened against major pests at Navsari Agricultural University (NAU), Navsari, Gujarat, India. Relationship of each character to pest incidence was established on the basis of correlation. Gladiator was considered as tolerant variety against thrips, blister beetle, castor semilooper, tussock moth and bud borer. Chinese rose was tolerant against aphid while, it was moderately susceptible against thrips (<i>R. syriacus</i>) and blister beetle. Barbone rose was moderately susceptible against castor semilooper and tussock moth. Overall, Gladiator was considered tolerant against majority of pests (except aphid). Plant growth habit exhibited significant positive correlation with aphid. Plant height had significant positive correlation with all the pests except aphid. Higher number of primary branches showed increased susceptibility to thrips, blister beetle, semilooper and tussock moth while, aphid was indirectly related to primary branches. Increased prickle density indicated increased thrips on leaves, larval populations of semilooper and tussock moth. Leaf colour exhibited negative relationship with semilooper, tussock moth and bud. Leaf area also influenced abundance of bud borer significantly. Increased leaf thickness showed decreased defoliator pests. Increased leaf glossiness showed decreased plant susceptibility to thrips, semilooper and tussock moth. Flower colour had negative relationship with semilooper, tussock moth and bud borer. Increased flower compactness indicated increased aphids and decreased thrips and blister beetle. Number of flower petals exhibited significant positive relationship with aphid and negative relationship with thrips and blister beetle. Lastly, number of flowers exhibited significant positive relationship with thrips, blister beetle, semilooper, tussock moth and bud borer while, it exhibited indirect relationship with aphid. Overall, most important biophysical traits of rose varieties grown under open field condition were plant height, number of primary branches, flower (compactness, number of petals and number of flowers/plant) which directly or indirectly influenced plant tolerance or susceptibility against major pests.

QTL Mapping of Traits Associated with Dual Resistance to the African Stem Borer (Busseola fusca) and Spotted Stem Borer (Chilo partellus) in Sorghum (Sorghum bicolor).

Sorghum (Sorghum bicolor (L.) Moench) is an important food crop in semi-arid tropics. The crop grain yield ranges from 0.5 t/ha to 0.8 t/ha compared to potential yields of 10 t/ha. The African stem borer Busseola fusca Fuller (Noctuidae) and the spotted stem borer Chilo partellus Swinhoe (Crambidae), are among the most economically important insect pests of sorghum. The two borers can cause 15% - 80% grain yield loss in sorghum. Mapping of QTLs associated with resistance traits to the two stem borers is important towards marker-assisted breeding. The objective of this study was to map QTLs associated with resistance traits to B. fusca and C. partellus in sorghum. 243 F9:10 sorghum RILs derived from ICSV 745 (S) and PB 15520-1 (R) were selected for the study with 4,955 SNP markers. The RILs were evaluated in three sites. Data was collected on leaf feeding, deadheart, exit holes, stem tunnels, leaf toughness, seedling vigour, bloom waxiness, and leaf glossiness. ANOVA for all the traits was done using Genstat statistical software. Insect damage traits and morphological traits were correlated using Pearson's correlation coefficients. Genetic mapping was done using JoinMap 4 software, while QTL analysis was done using PLABQTL software. A likelihood odds ratio (LOD) score of 3.0 was used to declare linkage. Joint analyses across borer species and sites revealed 4 QTLs controlling deadheart formation; 6 controlling leaf feeding damage; 5 controlling exit holes and stem tunneling damages; 2 controlling bloom waxiness, leaf glossiness, and seedling vigour; 4 conditioning trichome density; and 6 conditioning leaf toughness. Joint analyses for B. fusca and C. partellus further revealed that marker CS132-2 colocalised for leaf toughness and stem tunneling traits on QTLs 1 and 2, respectively; thus, the two traits can be improved using the same linked marker. This study recommended further studies to identify gene(s) underlying the mapped QTLs.

Morpho-physiological traits and leaf surface chemicals as markers conferring resistance to sorghum shoot fly (Atherigona soccata Rondani)

Sorghum shoot fly, Atherigona soccata,causes substantial economic losses in sorghum globally. Cultural practices and host plant resistance are effective measures for mitigating the losses caused by sorghum shoot fly. Therefore, we evaluated 32 sorghum genotypes consisting of a set of 10 restorer lines, 10 CMS (cytoplasmic male-sterile) lines and their respective maintainers exhibiting resistance/susceptibility to shoot fly along with resistant and susceptible checks under field conditions. The traits such as leaf glossiness, leaf sheath pigmentation, percentage plants with shoot fly deadhearts and number of shoot fly eggs per plant were used as morphological markers for selecting genotypes with resistance to shoot fly during the rainy and post rainy seasons of 2016 and 2017. The test material was also subjected to biochemical analysis (total soluble sugars, protein and tannin contents), while the leaf surface chemicals were analysed by GC–MS to identify the compounds associated with resistance/susceptibility to shoot fly. The genotypes differed significantly for all the traits, except percentage plants with shoot fly deadhearts during the 2016 rainy season. The genotypes ICSB 458, ICSA/B 467, ICSA/B 487, ICSA/B 14037, IS 18551 and ICSV 93046 exhibited moderate to high levels of resistance to shoot fly based on number of plants with shoot fly deadhearts, plants with shoot fly eggs and total number of shoot fly eggs. The shoot fly resistant genotypes ICSB 84, ICSA/B 467, ICSB 487, ICSB 14024, and IS 18551 had low shoot fly deadheart incidence, higher amounts of condensed tannins, soluble sugars, phenols and lower protein content as compared to the susceptible genotypes. Thirteen unique compounds were identified from leaf surface extracts by GC–MS which were associated with shoot fly resistance/susceptibility. While HPLC analysis revealed that Protocatechuic and coumaric acids were present in most of the sorghum genotypes, but their amounts were significantly greater in resistant as compared to the susceptible ones. The findings of the study highlight the importance of various morphological and biochemical traits conferring resistance to sorghum shoot fly, and these traits can be used as markers to identify shoot fly resistant genotypes for use in breeding programs.

Correlation study of traits associated with shoot fly resistance in recombinant inbred lines (RILs) population of sorghum [Sorghum bicolor (L.) Moench

The shoot fly resistance in sorghum appears to be a complex trait and depends upon the interaction of a number of component characters, which finally sum up in the expression of shoot fly resistance. The present study was conducted during Summer-2019 to assess the correlation and study the relationship of different plant characters with shoot fly resistance in sorghum. Observations were recorded on the shoot fly components traits viz., dead heart percentage and oviposition as well as the morphological characters viz., trichome density, leaf glossiness, seedling vigour, 100 seed weight and grain yield per plant. The experimental data were collected and analyzed for correlation. Shoot fly resistance was found to be significant and positively correlated with components traits viz., seedling vigour, glossiness and trichome density at the abaxial and the adaxial surface of leaves lamina. Whereas a hundred grains weight and grain yield per plant were showed strongly significant, but negatively correlated with dead heart percentage at 21, 28 DAE and oviposition% in 14, 21 DAE respectively. The strong correlation of grain yield and these traits could indicate that improvement of all the characters is possible simultaneously and might be used to select shoot fly-resistant lines from the segregating breeding materials for use in sorghum improvement.

Character association and path coefficient analysis of shoot fly resistance and yield components in sorghum (Sorghum bicolor (L.) Moench)

The present study was carried out to analyze and determine the component traits having strong association with shoot fly resistance and true contribution or mutual relationship toward the grain yield in sorghum. Sorghum RILs population, 110 lines were evaluated and the field experiment was conducted during Kharif season. Grain yield per plant recorded a strong negative correlation with days to 50% flowering, Per cent of oviposition at 14 DAE and dead heart per cent at 21, 28 DAE. Whereas, it showed significant positive correlation with hundred grain weight, seedling vigour, leaf glossinees and trichome density on both surface of leaves. Path coefficient analysis data showed that the characters, hundred grain weight (0.378), trichome density on abaxial leaf surface (0.257), per cent of oviposition at 21 DAE (0.208), dead heart per cent at 21 DAE (0.110), leaf glossiness (0.108) and trichome density on adaxial leaf surface (0.104) had positive direct effect on grain yield. Whereas, negatively direct effects were observed with number of eggs per seedling at 21 DAE (-0.192), dead heart per cent at 28 DAE (-0.190) and days to 50% flowering (-0.183) respectively. The characters, plant height, number of leaves per plant, leaf width and hundred grain weight were showed positive indirect effect on grain yield but stem girth, leaf length and days to 50% flowering had negative indirect effects. The obtained results from this investigation could help the selection for these traits and improve the shoot fly resistance and high yield varieties in sorghum.

Inheritance of resistance traits to African stem borer in grain sorghum

The African stem borer (Busseola fusca [Fuller]) is an important insect pest of cereals, mainly maize, sorghum and millets. The pest causes up to 80% reduction in grain yield, depending on the pest population in the field, cultivar and the management practices employed. This reduction in yield translates into food insecurity, especially in semi-arid lands (ASALs) where sorghum is cultivated by small holder farmers. This study investigated the inheritance of resistance traits to the African stem borers in grain sorghum in Kenya. The experimental material consisted of seventeen sorghum lines with varying levels of resistance to the African stem borer. The mating design employed was North Calorina Design 2, where 15 sorghum lines were used as females on two males. The crosses were evaluated in two seasons at University of Embu farm in 2011/2012 short and long seasons replicated twice. Artificial infestation with African stem borer neonates was done 30 days after planting using a camel brush. Data collected included stem borer damage and agro-morphological traits. Genetic analyses were performed using a line x tester method using Genstat statistical software. It was found that both additive and non-additive gene effects were important in conditioning resistance traits to the African stem borer. This implies that expression of high leaf glossiness, plant vigour and bloom waxiness in F1 hybrids is conditioned by additive genes and these traits can be used as morphological markers to select for resistance to the borer in sorghum. ICSB 464 x ICSB 473 was the best combiner for stem borer resistance and grain yield. Parents ICSA 464, ICSB 464 and ICSB 474, were among the good combiners for resistance to the stem borer. These parents can be utilised in developing superior sorghum hybrids resistant to the insect pest.Key words: Gene action, heritability, Sorghum bicolor

Evaluation of sorghum genotypes for their resistance to shoot fly Atherigona soccata

An experiment with sixteen sorghum genotypes including two checks was conducted to evaluate their reaction against shoot fly at Akola, during kharif 2016–17. Observations were made on the eggs, deadhearts, seedling vigour, leaf glossiness, trichome density, chlorophyll content and Bricks index. The results revealed that the seedling leaf glossiness score (SLGS) of 1.67 to 4.67 and these were significantly positively corelated with oviposition and deadhearts. Seedling vigour score (SVS) also was observed with a positive significant association with eggs and deadhearts on 14th and 28th days after emergence. The trichomes on abaxial (lower) surface was observed to be maximum with the resistant check IS-18551, and this showed a significant negative association with oviposition and deadhearts. Chlorophyll index had highly significant positive impact on the oviposition and deadhearts. Low Bricks indices were observed in the resistant lines.

Pattern of genetic inheritance of morphological and agronomic traits of sorghum associated with resistance to sorghum shoot fly, Atherigona soccata

Sorghum shoot fly, Atherigona soccata is an important pest of sorghum during the seedling stage, which influences both fodder and grain yield. To understand the nature of inheritance of shoot fly resistance in sorghum, we performed generation mean analysis using two crosses IS 18551 × Swarna and M 35-1 × ICSV 700 during the 2013–2014 cropping seasons. The F1, F2, BC1 and BC2 progenies, along with the parental lines were evaluated for agronomic and morphological traits associated with resistance/susceptibility to sorghum shoot fly, A. soccata. The cross IS 18551 × Swarna exhibited significant differences between the parents for shoot fly deadhearts (%) in the postrainy season. The progenies of this cross exhibited lower shoot fly damage, suggesting that at least one of the parents should have genes for resistance to develop shoot fly-resistant hybrids. Leaf glossiness, leafsheath pigmentation and plant vigor score during the seedling stage exhibited non-allelic gene interactions with dominant gene action, whereas 100 seed weight showed both additive and dominant gene interactions. Presence of awns showed recessive nature of the awned gene. Generation mean analysis suggested that both additive and dominance gene effects were important for most of the traits evaluated in this study, but dominance had a more pronounced effect.

Correlation studies for shoot fly [Atherigona soccata (Rondani)] resistance traits in F3 generation of Sorghum [Sorghum bicolor (L.) Moench

Field screening of 120 F3 families of sorghum lines against shoot fly resistance was carried out at Millet Breeding Station, Tamil Nadu Agricultural University during Summer 2018. Leaf trichome density on adaxial and abaxial leaf surfaces showed significant negative correlation with oviposition preference of shoot fly on 14 and 21 days after emergence and dead heart incidence on 21 and 28 DAE. Leaf glossiness and seedling vigour rating scale showed high significant positive correlation with shoot fly oviposition and dead hearts. Genotypic correlation confirmed that the number of trichomes on both surfaces of lamina, leaf glossiness and seedling vigour contributed resistance to shoot fly. Thus these characters can be used as selection criteria for breeding shoot fly resistance genotypes.

Inheritance of Resistance to Sorghum Shoot Fly, Atherigona soccata in Sorghum, Sorghum bicolor (L.) Moench.

Sorghum production is affected by a wide array of biotic constraints, of which sorghum shoot fly, Atherigona soccata is the most important pest, which severely damages the sorghum crop during the seedling stage. Host plant resistance is one of the major components to control sorghum shoot fly, A. soccata. To understand the nature of gene action for inheritance of shoot fly resistance, we evaluated 10 parents, 45 F1's and their reciprocals in replicated trials during the rainy and postrainy seasons. The genotypes ICSV 700, Phule Anuradha, ICSV 25019, PS 35805, IS 2123, IS 2146, and IS 18551 exhibited resistance to shoot fly damage across seasons. Crosses between susceptible parents were preferred for egg laying by the shoot fly females, resulting in a susceptible reaction. ICSV 700, ICSV 25019, PS 35805, IS 2123, IS 2146, and IS 18551 exhibited significant and negative general combining ability (gca) effects for oviposition, deadheart incidence, and overall resistance score. The plant morphological traits associated with expression of resistance/susceptibility to shoot fly damage such as leaf glossiness, plant vigor, and leafsheath pigmentation also showed significant gca effects by these genotypes, suggesting the potential for use as a selection criterion to breed for resistance to shoot fly, A. soccata. ICSV 700, Phule Anuradha, IS 2146 and IS 18551 with significant positive gca effects for trichome density can also be utilized in improving sorghums for shoot fly resistance. The parents involved in hybrids with negative specific combining ability (sca) effects for shoot fly resistance traits can be used in developing sorghum hybrids with adaptation to postrainy season. The significant reciprocal effects of combining abilities for oviposition, leaf glossy score and trichome density suggested the influence of cytoplasmic factors in inheritance of shoot fly resistance. Higher values of variance due to specific combining ability (σ2s), dominance variance (σ2d), and lower predictability ratios than the variance due to general combining ability (σ2g) and additive variance (σ2a) for shoot fly resistance traits indicated the predominance of dominance type of gene action, whereas trichome density, leaf glossy score, and plant vigor score with high σ2g, additive variance, predictability ratio, and the ratio of general combining ability to the specific combining ability showed predominance of additive type of gene action indicating importance of heterosis breeding followed by simple selection in breeding shoot fly-resistant sorghums. Most of the traits exhibited high broadsense heritability, indicating high inheritance of shoot fly resistance traits.

Components of resistance to sorghum shoot fly, Atherigona soccata

Sorghum shoot fly, Atherigona soccata is one of the major constraints in sorghum production, and host plant resistance is one of the components to control sorghum shoot fly. Thirty sorghum genotypes were evaluated for different mechanisms of resistance and morphological and agronomic traits during the rainy and postrainy seasons. The sorghum genotypes, Maulee, Phule Anuradha, M 35-1, CSV 18R, IS 2312, Giddi Maldandi, and RVRT 3 suffered lower shoot fly damage, and also exhibited high grain yield potential during the postrainy season. ICSB 433, ICSV 700, ICSV 25019, ICSV 25022, ICSV 25026, ICSV 25039, PS 35805, Akola Kranti, and IS 18551 exhibited antixenosis for oviposition and antibiosis against sorghum shoot fly, A. soccata. Leaf glossiness, plant vigor, leafsheath pigmentation and trichomes were associated with resistance/susceptibility to shoot fly. Path coefficient analysis indicated that direct effects and correlation coefficients of leaf glossiness, plant vigor, plant height, plant color and trichomes were in the same direction, suggesting that these traits can be used to select sorghum genotypes for resistance to shoot fly. Principal co-ordinate analysis based on shoot fly resistance traits and morphological traits placed the test genotypes into different groups. The genotypes placed in different groups can be used to increase the levels and broaden the genetic base of resistance to shoot fly. The environmental coefficient of variation and phenotypic coefficient of variation for shoot fly resistance and morphological traits were quite high, indicating season specific expression of resistance to sorghum shoot fly. High broadsense heritability, genetic advance and genotypic coefficient of variation suggested the predominance of additive nature of genes controlling shoot fly resistance, suggesting that pedigree breeding can be used to transfer shoot fly resistance into high yielding cultivars. This information will be useful for developing shoot fly-resistant high yielding cultivars for sustainable crop production.

Mechanisms and diversity of resistance to sorghum shoot fly, Atherigona soccata

AbstractSorghum shoot fly, Atherigona soccata, is one of the important pests of postrainy season sorghums. Of the 90 sorghum genotypes evaluated for resistance to this pest, RHRB 12, ICSV 713, 25026, 93046 and 25027, IS 33844‐5, Giddi Maldandi and RVRT 3 exhibited resistance in postrainy season, while ICSB 463, Phule Anuradha, RHRB 19, Parbhani Moti, ICSV 705, PS 35805, IS 5480, 5622, 17726, 18368 and 34722, RVRT 1, ICSR 93031 and Dagidi Solapur showed resistance in rainy season, suggesting season‐specific expression of resistance to A. soccata. ICSB 461, ICSB 463, Phule Yasodha, M 35‐1, ICSV 700, 711, 25010, 25019 and 93089, IS 18662, Phule Vasudha, IS 18551 and 33844‐5 and Barsizoot had fewer deadhearts than plants with eggs across seasons, suggesting antibiosis as one of the resistance mechanism. Five genotypes exhibited resistance with high grain yield across seasons. Correlation, path and stepwise regression analyses indicated that leaf glossiness, seedling vigour, trichome density, oviposition and leaf sheath pigmentation were associated with the expression of resistance/susceptibility to shoot fly, and these can be used as marker traits to select and develop shoot fly‐resistant sorghums.

Stability of resistance to sorghum shoot fly, Atherigona soccata

Sorghum shoot fly, Atherigona soccata is one of the most important pests of dual-purpose sorghums during the postrainy season in India. Therefore, it is important to identify stable sources of resistance to develop cultivars with shoot fly resistance and adaptation to postrainy season. We evaluated 190 lines adapted to the postrainy season across five locations, of which 30 lines were identified with resistance to A. soccata. These lines were further evaluated for three seasons across five locations to identify lines with stable resistance to this pest across seasons and locations. Data were recorded on oviposition non-preference, deadheart incidence, recovery resistance, morphological traits (leaf glossiness, seedling vigor, plant height and days to 50% flowering), and grain yield. The sorghum genotypes CSV 22, ICSB 422, ICSB 425, ICSB 428, ICSB 432, ICSB 458, ICSB 463, IS 2312, IS 5480, IS 18662, Phule Chitra, RSV 1093, IS 18551, and RSV 1235 exhibited resistance to shoot fly damage across seasons, of which ICSB 425, ICSB 428, ICSB 432, IS 2312, IS 5480, and IS 18551 showed non-preference for oviposition. Six genotypes (ICSB 425, IS 2312, IS 18662, RSV 1090, RSV 1093, and IS 18551) also showed good recovery resistance following shoot fly damage. Principal coordinate analysis placed the maintainer lines (B-lines) with shoot fly resistance in two clusters with ICSB 422, ICSB 432, ICSB 435, ICSB 456 and ICSB 458 in one cluster and ICSB 425, ICSB 428 and ICSB 463 in the other; the open pollinated varieties/germplasm lines (restorers) were placed in a different group (CSV 22, IS 5480, IS 2312 and RSV 1093), suggesting the possibilities for developing hybrids with adaptation to the postrainy season. Based on regression coefficient and deadheart incidence, the genotypes IS 2312, ICSB 425, RSV 1090 and ICSB 428 were stable in expression of resistance to shoot fly across seasons and locations. The genotypes CSV 22 and RSV 1093 exhibited high grain yield potential and resistance to shoot fly damage, while Phule Yashoda, IS 2312, RSV 1235, and ICSV 574 were moderately resistant to shoot fly damage, but had high grain yield potential. These genotypes can be used in sorghum improvement for developing cultivars with shoot fly resistance, high grain yield and adaptation to postrainy season.

Evaluation of sorghum genotypes for shoot fly resistance: morpho physiological characters

The results revealed that out of 30 entries evaluated against shoot fly, three genotypes viz. ICSB 425, ICSB 422 and IS 2312 were at par with resistant check, recording 35.19% infestation, they were categorized as resistant. As far as the role of morpho- physiological characters of plant in shoot fly resistance was concern, the leaf glossiness mainly acts as non-preference mechanism for oviposition and negatively associated with both oviposition and dead hearts of shoot fly. Seedling vigor revealed significant positive co-relation with shoot fly oviposition whereas non-significant negative co-relation with dead hearts. Highly significant and negative association was observed between trichome density at adaxial and abaxial leaf lamina. Genotypic correlation confirmed that the trichome density on both the surface of leaf lamina and leaf glossiness contributed resistance to shoot fly.

Development, genetic mapping of candidate gene-based markers and their significant association with the shoot fly resistance quantitative trait loci in sorghum [Sorghum bicolor (L.) Moench

The associations of candidate genes with quantitative trait loci (QTL) for insect resistance provide primary insight into the molecular mechanisms of resistance. The objectives of the present study were to genetically map the candidate genes and identify their association with shoot fly resistance, and update the genetic map with new markers to locate additional QTL. In this study, 80 candidate gene (CG)-based markers were developed, targeting the seven most important shoot fly resistance genomic regions reported in our previous study. Of the 17 polymorphic CGs, the allelic polymorphisms of seven genes were significantly associated with 18 major QTL for component traits of resistance in multiple QTL mapping (MQM), and two genes in the single-marker analysis. MQM with an updated map revealed 20 new QTL with LOD and R2 (%) values ranging from 2.6 to 15.6 and 5.5 to 34.5 %, respectively. The susceptible parent 296B contributed resistance at 10 QTL. Interestingly, an orthologous insect resistance gene Cysteine protease-Mir1 (XnhsbmSFC34/SBI-10), previously presumed to be a CG based on synteny with maize, was significantly associated with major QTL for all traits (except seedling vigor) explaining 22.1 % of the phenotypic variation for deadhearts%, a direct measure of shoot fly resistance. Similarly, a NBS–LRR gene (XnhsbmSFCILP2/SBI-10), involved in rice brown planthopper resistance, was associated with deadhearts% and number of eggs per plant. Beta-1,3-glucanase (XnhsbmSFC4/SBI-10), involved in aphid and brown planthopper resistance, was associated with deadhearts% and leaf glossiness. Comparative QTL analysis revealed the existence of common QTL for shoot fly and other important sorghum insect pests such as greenbug, head bug, and midge. Finally, the associated CGs should aid in elucidating the molecular basis of resistance, high-resolution mapping, and map-based cloning of major QTL, besides providing powerful gene tags for marker-assisted selection of shoot fly resistance.