PDF(Pubmed)
Abstract：
Guava (Psidium guajava L.) is an important fruit crop of the Indian sub-continent, with potential for improvements in quality and yield. The goal of the present study was to construct a genetic linkage map in an intraspecific cross between the elite cultivar \'Allahabad Safeda\' and the Purple Guava landrace to identify the genomic regions responsible for important fruit quality traits, viz., total soluble solids, titratable acidity, vitamin C, and sugars. This population was phenotyped in field trials (as a winter crop) for three consecutive years, and showed moderate-to-high values of heterogeneity coefficients along with higher heritability (60.0%-97.0%) and genetic-advance-over-mean values (13.23%-31.17%), suggesting minimal environmental influence on the expression of fruit-quality traits and indicating that these traits can be improved by phenotypic selection methods. Significant correlations and strong associations were also detected among fruit physico-chemical traits in segregating progeny. The constructed linkage map consisted of 195 markers distributed across 11 chromosomes, spanning a length of 1,604.47 cM (average inter-loci distance of 8.80 markers) and with 88.00% coverage of the guava genome. Fifty-eight quantitative trait loci (QTLs) were detected in three environments with best linear unbiased prediction (BLUP) values using the composite interval mapping algorithm of the BIP (biparental populations) module. The QTLs were distributed on seven different chromosomes, explaining 10.95%-17.77% of phenotypic variance, with the highest LOD score being 5.96 for qTSS.AS.pau-6.2. Thirteen QTLs detected across multiple environments with BLUPs indicate stability and utility in a future breeding program for guava. Furthermore, seven QTL clusters with stable or common individual QTLs affecting two or more different traits were located on six linkage groups (LGs), explaining the correlation among fruit-quality traits. Thus, the multiple environmental evaluations conducted here have increased our understanding of the molecular basis of phenotypic variation, providing the basis for future high-resolution fine-mapping and paving the way for marker-assisted breeding of fruit-quality traits.
摘要：
番石榴（PsidiumguajavaL.）是印度次大陆的重要水果作物，具有提高质量和产量的潜力。本研究的目的是在优良品种“阿拉哈巴德·萨夫达”和紫色番石榴地方品种之间的种内杂交中构建遗传连锁图谱，以确定负责重要果实品质性状的基因组区域，viz.,总可溶性固体，可滴定酸度，维生素C,和糖。该种群在田间试验（作为冬季作物）中连续三年进行表型鉴定，并表现出异质性系数的中高值以及较高的遗传力（60.0％-97.0％）和遗传-超平均值（13.23％-31.17％），表明环境对果实品质性状表达的影响最小，并表明这些性状可以通过表型选择方法得到改善。在分离后代的果实理化性状中也发现了显着的相关性和强关联。构建的连锁图谱由分布在11条染色体上的195个标记组成，长度为1,604.47cM（平均基因座间距离为8.80个标记），番石榴基因组覆盖率为88.00％。使用BIP（双亲种群）模块的复合间隔作图算法，在具有最佳线性无偏预测（BLUP）值的三个环境中检测到58个数量性状基因座（QTL）。QTL分布在7个不同的染色体上,解释10.95%-17.77%的表型变异，qTSS的最高LOD评分为5.96。AS.pau-6.2.使用BLUP在多个环境中检测到的13个QTL表明，在未来的番石榴育种计划中具有稳定性和实用性。此外，具有影响两个或多个不同性状的稳定或共同个体QTL的七个QTL簇位于六个连锁群（LGs）上，解释果实品质性状之间的相关性。因此，这里进行的多次环境评估增加了我们对表型变异的分子基础的理解，为今后的高分辨率精细作图奠定基础，为果实品质性状的标记辅助育种铺平了道路。
