Autogamous Nature Research Articles

Genomic Evaluation of Coffea arabica and Its Wild Relative Coffea racemosa in Mozambique: Settling Resilience Keys for the Coffee Crop in the Context of Climate Change.

Climate change is negatively affecting the coffee value chain, with a direct effect on approximately 100 million people from 80 countries. This has been attributed to the high vulnerability of the two-mainstream species, Coffea arabica and Coffea canephora, to extreme weather events, with notable uneven increases in market prices. Taking into account the narrow genetic plasticity of the commercial coffee cultivars, wild-relatives and underutilized Coffea species are valuable genetic resources. In this work, we have assessed the occurrence of Coffea species in to understand the degree of genetic relationships between Coffea species in the country, as well as the patterns of genetic diversity, differentiation, and genetic structure. Only one wild species was found, C. racemosa, which showed a high level of genetic separation with C. arabica, based on plastid, as well as SSR and SNP analysis. C. arabica presented low levels of diversity likely related to their autogamous nature, while the allogamous C. racemosa presented higher levels of diversity and heterozygosity. The analysis of the functional pathways based on SNPs suggests that the stress signaling pathways are more robust in this species. This novel approach shows that it is vital to introduce more resilient species and increase genomic diversity in climate-smart practices.

Effectiveness and efficiency of electron beam in comparison with gamma rays and ethyl methane sulfonate mutagens in cowpea

Cowpea is the poor man's crop that lacks variability due to its autogamous nature. Induced mutation serves as a potential source in the induction of variability in crops. On the other hand, the effectiveness and efficiency of mutagens will vary between species and even varieties. In the present study, a novel mutagen electron beam was used in cowpea for the first time along with commonly used mutagens gamma rays (physical) and ethyl methanesulfonate (chemical). The biological damages on eight quantitative characters in M1 generation and chlorophyll mutants in M2 generation were recorded. Two popular varieties viz., P 152 and VBN 1 constituted as the biological material of study. The rate of reduction in biological damage on quantitative characters was directly proportional to the dose of mutagen irrespective of the varieties and mutagens used. Physical mutagens showed the highest biological damage (EB- 37.5% and G- 37.3% overall reduction from control) than chemical mutagen (EMS- 30.4%). Comparing the physical mutagens at similar doses, 200 Gy or 300 Gy of electron beam showed more biological damage than 200 Gy or 300 Gy of gamma rays. Eleven different types of chlorophyll mutants were identified in the M2 generation. Xantha is the most occurred chlorophyll mutants (44.44%), while aurea and yellow viridis have least occurred mutants. Chemical mutagen (EMS) is considered to be the most effective (6.47%) and efficient mutagen (27.09%) based on the chlorophyll mutants and it was followed by an electron beam and gamma rays. Among the physical mutagens, electron beam showed the highest biological damage (37.50% overall reduction from control) and higher effectiveness and efficiency (3.80% and 23.38%) compared to gamma rays (1.87% and 13.38%). Hence, the electron beam can also be used as an effective mutagen in creating variation in cowpea and other crops as it is highly effective, cost less and safe mutagen.

Market‐led options to scale up legume seeds in developing countries: Experiences from the Tropical Legumes Project

AbstractThere are several hurdles to ensure sustainable seed production and consistent flow of improved legume varieties in sub‐Saharan Africa (SSA) and South Asia (SA). The unreliable demand, autogamous nature of most of the grain legumes, and slow variety replacement rate by smallholder farmers do not provide strong incentive for private seed companies to invest in legume seed business. Unless a well thought‐out and comprehensive approach to legume seed delivery is developed, current seed shortages will continue, eroding emerging market opportunities. The experiences reported here are collated through a 10‐year partnership project, the Tropical Legumes in SSA and SA. It fostered innovative public–private partnerships in joint testing of innovative market‐led seed systems, skills and knowledge enhancement, de‐risking private sector initiatives that introduced in new approaches and previously overlooked entities in technology delivery. As new public and private seed companies, individual seed entrepreneurs and farmer organizations emerged, the existing ones enhanced their capacities. This resulted in significant rise in production, availability and accessibility of various seed grades of newly improved and farmer demanded legume varieties in the target countries.

On the reproductive biology of Salacia fruticosa Wall. ex M.A. Lawson - an endemic medicinal plant of the Western Ghats, india

Salacia fruticosa Wall. ex M.A. Lawson, an endemic species was studied for the reproductive biology as this species showed reduced fruit set and natural regeneration. The stigma-anther proximity, an extremely low number of pollen grains, a short period of pollen viability, a sparse incidence of pollinators, protandrous and facultative autogamous nature of the flowers and a low percent in fruit set were identified as biological constraints for the species. The incidence of seed pest was added to the poor seed and seedling bank and accelerated rarity process of the species.

Genetic diversity, linkage disequilibrium, and population structure in a panel of Brazilian rice accessions.

Narrowing of genetic diversity and the quantitative nature of most agronomic traits is a challenge for rice breeding. Genome-wide association studies have a great potential to identify important variation in loci underlying quantitative and complex traits; however, before performing the analysis, it is important to assess parameters of the genotypic data and population under study, to improve the accuracy of the genotype-phenotype associations. The aim of this study was to access the genetic diversity, linkage disequilibrium, and population structure of a working panel of Brazilian and several introduced rice accessions, which are currently being phenotyped for a vast number of traits to undergo association mapping. Ninety-four accessions were genotyped with 7098 SNPs, and after filtering for higher call rates and removing rare variants, 93 accessions and 4973 high-quality SNPs remained for subsequent analyses and association studies. The overall mean of the polymorphic information content, heterozygosity, and gene diversity of the SNPs was comparable to other rice panels. The r2 measure of linkage disequilibrium decayed to 0.25 in approximately 150kb, a slow decay, explained by the autogamous nature of rice and the small size of the panel. Regarding population structure, eight groups were formed according to Bayesian clustering. Principle components and neighbor-joining analyses were able to distinguish part of the groups formed, mainly regarding the sub-species indica and japonica. Our results demonstrate that the population and SNPs are of high quality for association mapping.

English

Coffee is the second most valuable commodity exported by developing countries, and supports the livelihood of more than 75 million people. There are limitations to preference for established cultivars due to the autogamous nature of the crop thereby making improvements via conventional breeding of many years to produce a new cultivar difficult. Mutation breeding can overcome these obstacles. One of the first steps in mutation breeding is to determine radio-sensitivity so that optimal irradiation treatments can be determined. Three cultivars: Kents, Mundo novo and Geisha were sourced from the coffee germplasm collection at the Mambilla Plateau substation of the institute, Taraba State, Nigeria. The biological effect of the physical was studied in the selected cultivars of Coffea arabica after the rooted seedlings were treated with various doses of Gamma rays: 0, 5, 10, 15, 20 and 25 Gy. Success takes percentage and seedling vigour were used as measures of radio-sensitivity at 4 weeks after settings (WAS), 8, 12, and 16 WAS. The results showed that genotype of the cultivars and dosage of irradiation significantly influenced response to irradiation treatments (p < 0.05). The effect of the irradiation on treated cultivars was inversely proportional to the emergence of the success takes, plant height, root length, number of roots and number of leaves. The optimal mutation treatment (LD50) of M1V1 cuttings was in the range of 12 Gy in all the treated Arabica varieties an indication to buttress the narrow genetic base with reference to the similarity of their evolutionary trends. This work provides data on dose treatments for mutation induction in coffee, which may be exploited for coffee improvement.   Key words: Cultivars, autogamous, mutation, irradiation and genotypes.

Model Legumes: Functional Genomics Tools in Medicago truncatula.

Many researchers have sought along the last two decades a legume species that could serve as a model system for genetic studies to resolve specific developmental or metabolic processes that cannot be studied in other model plants. Nitrogen fixation, nodulation, compound leaf, inflorescence and plant architecture, floral development, pod formation, secondary metabolite biosynthesis, and other developmental and metabolic aspects are legume-specific or show important differences with those described in Arabidopsis thaliana, the most studied model plant. Mainly Medicago truncatula and Lotus japonicus were proposed in the 1990s as model systems due to their key attributes, diploid genome, autogamous nature, short generation times, small genome sizes, and both species can be readily transformed. After more than decade-long, the genome sequences of both species are essentially complete, and a series of functional genomics tools have been successfully developed and applied. Mutagens that cause insertions or deletions are being used in these model systems because these kinds of DNA rearrangements are expected to assist in the isolation of the corresponding genes by Target-Induced Local Lesions IN Genomes (TILLING) approaches. Different M. truncatula mutants have been obtained following γ-irradiation or fast neutron bombardment (FNB), ethyl-nitrosourea (ENU) or ethyl-methanesulfonate (EMS) treatments, T-DNA and activation tagging, use of the tobacco retrotransposon Tnt1 to produce insertional mutants, gene silencing by RNAi, and transient post-transcriptional gene silencing by virus-induced gene silencing (VIGS). Emerging technologies of targeted mutagenesis and gene editing, such as the CRISPR-Cas9 system, could open a new era in this field. Functional genomics tools and phenotypic analyses of several mutants generated in M. truncatula have been essential to better understand differential aspects of legumes development and metabolism.

Detection of genetic components of variation for some biometrical traits in Linum usitatissimum L. in sub-mountain Himalayan region

Gene action for seed yield and its component traits in linseed were studied using triple test cross analysis. The main objective was to determine the nature and magnitude of genic effects for different biometrical traits under variable environments that could support further improvements of linseed productivity using appropriate breeding methodology. Epistasis was observed for technical height in E1, 1,000-seed weight in both the environments, plant height, 1,000-seed weight and biological yield per plant in combined over environments. Both [i] and [j + l] type of epistatic interactions were significant for all these traits except technical height and 1,000-seed weight in E1, for which only [i] type of interaction was significant. Additive (D) gene action was significant for most of the traits whereas non-additive (H) gene action was significant for only seeds per capsule (E1, E2 & E3), 1,000-seed weight (E2 & E3), technical height (E2) and biological yield per plant (E3). Additive type of gene action was preponderant for plant height (E1, E2 & E3), technical height (E1, E2 & E3), capsules per plant (E3), seed yield per plant (E1 & E3), 1,000-seed weight (E1, E2 & E3), straw yield per plant (E1 & E3), and harvest index (E1, E2 & E3), whereas non-additive type of gene action was preponderant for seeds per capsule (E1, E2 & E3), and biological yield per plant (E3). The presence of additive gene action for most of the traits including seed yield per plant implies that early generation selection may be useful for the improvement of these traits. However, for traits showing both additive and dominance components of variance, heterosis breeding may be useful but chances of exploiting hybrid vigour through hybrid varieties in linseed due to its autogamous nature are bleak at present. The autogamous nature of crop and absence of genetic-cytoplasmic male sterility warrants diallel selective mating/biparental mating or recurrent selection followed by pedigree method of selection for its improvement.

A comparative study of the reproductive character and genetic diversity of an autogamous Tylophora matsumurae and its progenitor Tylophora tanakae (Apocynaceae-Asclepiadoideae)

Reproductive character and genetic diversity were investigated for an autogamous species of Tylophora matsumurae endemic to the Ryukyu Islands and its progenitor species T. tanakae. Approximately one-fourth of bagged flowers set fruits in T. matsumurae, although no fruits were obtained from bagged flowers in T. tanakae. In situ pollen tube germination was observed with high frequency in all five populations examined in T. matsumurae. Furthermore, in T. matsumurae, anther sacs were not dehisced even at anthesis. These results suggest the highly autogamous nature of T. matsumurae. No allozymic variation was detected in all seven populations examined in T. matsumurae. The phenogram constructed using the neighbor-joining method based on Nei's unbiased genetic distance indicated that T. matsumurae clustered with the Okinoerabu Island population of T. tanakae. The estimated outcrossing rate of four populations of T. tanakae varied from 0.18 to 0.59. It is probable that T. matsumurae had been derived from the predominantly self-pollinating population of T. tanakae, and rapidly enlarged its distribution area.

Inheritance of evolved glyphosate resistance in Conyza canadensis (L.) Cronq.

N-(phosphonomethyl)glycine (glyphosate) resistance was previously reported in a horseweed [Conyza (=Erigeron) canadensis (L.) Cronq.] population from Houston, DE (P (0) (R) ). Recurrent selection was performed on P (0) (R) , since the population was composed of susceptible (5%) and resistant (95%) phenotypes. After two cycles of selection at 2.0 kg ae glyphosate ha(-1), similar glyphosate rates that reduced plant growth by 50%, glyphosate rates that inflicted 50% mortality in the population, and accumulations of half of the maximum detectable shikimic acid concentration were observed between the parental P (0) (R) and the first (RS(1)) and second (RS(2)) recurrent generations. In addition, RS(1) and RS(2) did not segregate for resistance to glyphosate. This suggested that the RS(2) population comprised a near-homozygous, glyphosate-resistant line. Whole-plant rate responses estimated a fourfold resistance increase to glyphosate between RS(2) and either a pristine Ames, IA (P (0) (P) ) or a susceptible C. canadensis population from Georgetown, DE (P (0) (S) ). The genetics of glyphosate resistance in C. canadensis was investigated by performing reciprocal crosses between RS(2) and either the P (0) (P) or P (0) (S) populations. Evaluations of the first (F(1)) and second (F(2)) filial generations suggested that glyphosate resistance was governed by an incompletely dominant, single-locus gene (R allele) located in the nuclear genome. The proposed genetic model was confirmed by back-crosses of the F(1) to plants that arose from achenes of the original RS(2), P (0) (P) , or P (0) (S) parents. The autogamous nature of C. canadensis, the simple inheritance model of glyphosate resistance, and the fact that heterozygous genotypes (F(1)) survived glyphosate rates well above those recommended by the manufacturer, predicted a rapid increase in frequency of the R allele under continuous glyphosate selection. The impact of genetics on C. canadensis resistance management is discussed.

The Reproductive Biology of Agalinis auriculata (Michx.) Raf. (Orobanchaceae), a Threatened North American Prairie Inhabitant

We examined the reproductive biology of the hemiparasitic threatened prairie species, Agalinis auriculata (Michx.) Raf., eared‐false foxglove (Orobanchaceae), in two populations located at the Midewin National Tallgrass Prairie in Illinois. Populations flowered from late August through mid‐September, and individual plants bloomed for an average of 8 d; typically two flowers per plant opened each day. Buds opened in the early morning hours between 0530 and 0630 hours, with the anthers dehiscing at this time. Stigmas reached peak receptivity ca. 2 h later, followed by corolla abscission shortly afterward. Breeding system experiments indicated that flowers readily self‐pollinate without reduction in fruit set, seed set, or seed mass compared with outcrossed individuals. The primary floral visitors were Bombus impatiens (Apidae) and Melissodes bimaculata (Anthophoridae). On the basis of phenological and breeding system data, A. auriculata is a self‐compatible species that self‐pollinates in the absence of floral visitors; however, when pollinators are present, outcrossing can occur. The autogamous nature, in combination with a healthy reproductive output, indicates that the decline of this species might result from other aspects of its biology, such as seed germination and availability of host plants.

Cost of commercial seed production in hybrid ssame

The floral biology of sesame, despite its autogamous nature, is favourably suited for developing hybrids. To produce hybrid seeds in sesame, different techniques are tried. In the present study, attempt were made to produce large quantities of hybrid seed by hand emasculation and pollination method. It was found that 98.64 per cent of the total cost of hybrid seed production was spent towards emasculation and crossing. On an average, one labour could attend 450 and 275 flower buds respectively for emasculation and pollination in an hour. Only 57 per cent capsule set was recorded and the number of seeds formed in the crossed capsule was also less. The production cost of hybrid seeds was worked out to be Rs. 534.00 per kg.

EVALUATION OF GENOTYPES ARISING FROM F2 GENERATION SEGREGATIONS IN DWARF X TALL CROSSES OF COCOSNUCIFERA

Twenty seven F2 generation palms belonging to selfed and crossed families of F1, palms arising from a cross between dwarf green and Tall in Cocos Nucifera were studied for vegetative, reproductive and yield characters. The objective was to study the segregation patterns of the introgressed characters of the Dwarf x Tall hybrid in the F2 generation and, to investigate the effects of selfing. An average of four palms were studied in each F2 family.
 
 The time takenfor initial flowering was spread in a greater range in F2 families arising from selfed F1, compared to F2 families originating from crossing two different F1 palms. The pollination behaviour of the palms revealed to be segregating in two selfed F2 families. Two palms, one in each F2 family (selfed F1) were found to be autogamous with overlapping male and female phases whilst the rest showed allogamy. Recombination of the autogamous nature along with the Tall characters were observed in the F2 palms. The results suggest that the genetic control of the pollination behat4our is polygenic and an aggregate of several recessive genes are responsible for the autogamous nature of the palm. Certain genotypes arising from selfed families recorded high husked nut weights (650 ‑ 700 gms) compared to crossed families indicating their resistance to in breeding depression. The possibility of extracting recombined lines with desirable characters in order to improve the Sri Lankan Dwarf x Tall is also discussed

Variation and Taxonomy of Phytolacca americana and P. rigida in the Southeastern United States

CAULKINs, D. B. AND R. WYATT (Department of Botany, University of Georgia, Athens, GA 30602). Variation and taxonomy of Phytolacca americana and P. rigida in the southeastern United States. Bull. Torrey Bot. Club 117: 357-367. 1990.-Phytolacca americana L. is a common native weed of the eastern United States, ranging from Quebec and Ontario south to northeastern Mexico. Previous authors have disagreed as to the status of a second taxon, P. rigida Small, which is distinguished from P. americana by erect, rather than drooping racemes and pedicels that are shorter than the berries. In addition, P. rigida is restricted to Florida and the Atlantic and Gulf coasts. Artificial cross-pollinations between plants of the two taxa yielded viable seeds, but interpretation of this result is equivocal because of the strongly autogamous nature of the plants. Flavonoid profiles of the two taxa were found to be indistinguishable, consisting of six glycosides of the flavonols quercetin and kaempferol. No taxonomically useful differences were detected in salinity tolerance or seed germination. The region between the Upper Coastal Plain and Quaternary deposits of the Lower Coastal Plain appears to form an ecological barrier between the two taxa. Analyses of 14 morphological characters in 36 populations from the Coastal Plain of the southeastern United States showed that P. rigida is distinct from P. americana in several characters. It is not, however, sufficiently distinct to deserve recognition as a separate species. Therefore, a new combination is proposed: Phytolacca americana var. rigida.