Basis Of Yield-related Traits Research Articles

Genome wide association analysis for yield related traits in maize

BackgroundUnderstanding the genetic basis of yield related traits contributes to the improvement of grain yield in maize.ResultsUsing 291 excellent maize inbred lines as materials, six yield related traits of maize, including grain yield per plant (GYP), grain length (GL), grain width (GW), kernel number per row (KNR), 100 kernel weight (HKW) and tassel branch number (TBN) were investigated in Jinan, in 2017, 2018 and 2019. The average values of three environments were taken as the phenotypic data of yield related traits, and they were statistically analyzed. Based on 38,683 high-quality SNP markers in the whole genome of the association panel, the MLM with PCA model was used for genome-wide association analysis (GWAS) to obtain 59 significantly associated SNP sites. Moreover, 59 significantly associated SNPs (P < 0.0001) referring to GYP, GL, GW, KNR, HKW and TBN, of which 14 SNPs located in yield related QTLs/QTNs previously reported. A total of 66 candidate genes were identified based on the 59 significantly associated SNPs, of which 58 had functional annotation.ConclusionsUsing genome-wide association analysis strategy to identify genetic loci related to maize yield, a total of 59 significantly associated SNP were detected. Those results aid in our understanding of the genetic architecture of maize yield and provide useful SNPs for genetic improvement of maize.

RAPID SCREENING OF WHEAT GERMPLASM FOR DROUGHT PRONE ENVIRONMENT

Wheat (Triticum aestivum L.) has been cultivated over wider ranges of climatic changes. Changing rainfall pattern has been drastically affecting its yield and production, especially in the areas where there are least rainfalls; irrigation water is not available and are highly dependent upon conserved soil moisture. Development of drought tolerant genotypes for such drought prone areas essential for the farmers, there is a dire need to exploit the rapid and efficient methods of screening large germplasm in wheat. In the present study one hundred and eight genotypes were screened by “PEG Assay Germination Test”. PEG assay proved an effective method for screening the large germplasm as fifteen accessions were finally identified are finally selected from 108 accessions. The promising fifteen genotypes with five checks were evaluated in greenhouse pot experiment on the basis of yield related traits and proline content. Among the fifteen accessions, “12160” accession revealed the better performance in all traits especially for grain weight and proline content.

Characterization of wheat landraces and commercial cultivars based on morpho-phenological and agronomic traits

Wheat landraces are valuable genetic resource for diversity and specific adaptation to local environmental conditions as well as increasing agronomic traits in breeding programs. Admittedly, this type of genotypes has become more crucial to face the challenges of recent climate change. The aim of this study was to investigate the genetic diversity among Egyptian bread wheat landraces and commercial cultivars based on morpho-phenological and agronomic characters. Thirty-two wheat landraces were collected from eleven Egyptian provinces through collecting trips during 1987 to 1999 and, in addition, three commercial cultivars were evaluated all for fifteen qualitative and quantitative characters. Wide genetic diversity was detected based on evaluated morphological characters was observed among the landraces compared to commercial cultivars. Various landraces exhibited strong glaucosity on flag leaf, culm and ear, which is crucial character especially under dry and hot cultivation conditions as Mediterranean region. Furthermore, considerable variation among tested genotypes was demonstrated on the basis of yield-related traits and they were classified into four groups (A–D) from very high-yielding to low-yielding genotypes. Wheat landraces number 3, 8, 14, 27, 29, 33 and 35 exhibited superiority for earliness, grain yield/plant and its components compared to commercial cultivars (number 18, 19 and 20). The association among morpho-phenological and agronomic characters was studied according to principal component analysis. The evaluated characters were divided into four groups. Certain morphological characters (coleoptiles anthocyanin coloration and awns or scurs at tip of ear length) alongside the phenological characters (days to heading and maturity) and certain agronomic characters (plant height and 1000-grain weight) displayed strong association with grain yield/plant. Furthermore, estimated broad sense heritability was high for plant height, number of grains/spike, 1000-grain weight, days to heading, moderate for days to maturity and grain yield/plant presented and low for number of spikes/plant.

Agro-Morphological Variation in Some Iranian Melon (Cucumis melo L.) Genotypes Revealed by Multivariate Analysis

Diversity of 9 local Iranian genotypes of melon was studied based on 28 quantitative and qualitative agro-morphological traits, using multivariate statistical methods. Analysis of variance showed significant differences between genotypes for all quantitative traits. However, the studied melon genotypes were previously clustered in two main groups of inodorous and cantalopensis, cluster analysis classified them in four different groups based on all traits, in particular outlaying Shadegani genotype from Inodorous group. Clustering was also supported by principal components analysis (PCA). The first two PCs contributed 60% of the total variability and demonstrated variations mainly on the basis of yield related traits including fruit number, day to flower, day to harvest, fruit weight, fruit length and other distinctive traits such as rind pattern, peduncle attachment strength, fruit firmness and aroma. Accordingly, agro-morphological traits could be used for variation studies in melons and results might be useful for improving breeding programs.

Combining ability analysis for evaluation of maize hybrids under drought stress

The present study was conducted to evaluate the genetic basis of yield related traits under drought conditions. A high heritability and genetic advance was found for plant height, 100-grain weight, grain rows per cob and grain yield per plant, suggesting that the selection of high yielding maize genotypes is possible through this approach. The high specific combining ability of W64SP, A495, A509 and A50-2 suggested that the pre-screening of inbred lines may be an efficient approach to develop higher yielding maize hybrids through heterosis breeding under drought.

Identification of candidate genes associated with positive and negative heterosis in rice.

To identify the genes responsible for yield related traits, and heterosis, massively parallel signature sequencing (MPSS) libraries were constructed from leaves, roots and meristem tissues from the two parents, ‘Nipponbare’ and ‘93-11’, and their F1 hybrid. From the MPSS libraries, 1–3 million signatures were obtained. Using cluster analysis, commonly and specifically expressed genes in the parents and their F1 hybrid were identified. To understand heterosis in the F1 hybrid, the differentially expressed genes in the F1 hybrid were mapped to yield related quantitative trait loci (QTL) regions using a linkage map constructed from 131 polymorphic simple sequence repeat markers with 266 recombinant inbred lines derived from a cross between Nipponbare and 93-11. QTLs were identified for yield related traits including days to heading, plant height, plant type, number of tillers, main panicle length, number of primary branches per main panicle, number of kernels per main panicle, total kernel weight per main panicle, 1000 grain weight and total grain yield per plant. Seventy one QTLs for these traits were mapped, of which 3 QTLs were novel. Many highly expressed chromatin-related genes in the F1 hybrid encoding histone demethylases, histone deacetylases, argonaute-like proteins and polycomb proteins were located in these yield QTL regions. A total of 336 highly expressed transcription factor (TF) genes belonging to 50 TF families were identified in the yield QTL intervals. These findings provide the starting genomic materials to elucidate the molecular basis of yield related traits and heterosis in rice.