Table_2_Volatile profiling as a potential biochemical marker for validation of gamma irradiation derived putative mutants in polyembryonic genotypes of mango (Mangifera indica L.).docx

IntroductionPutative mutants were generated through gamma irradiation in the polyembryonic mango genotype Nekkare. The putative mutant progenies along with control seedlings and mother plants were evaluated by comparing the compositions and relative proportions of their major volatile compounds.MethodsVolatile profiling was done using headspace-solid phase micro-extraction (HS SPME) method coupled with gas chromatography–mass spectrometry (GC-MS MS). Furthermore, characterisation of putative mutants and control seedlings was carried out using simple sequence repeat (SSR) markers to ascertain the genetic diversity present in the samples under study.ResultsMonoterpenes were the most abundant volatile compound in all the studied samples (ranging from 34.76% to 91.41%) out of which I-Phellandrene and cis-Ocimene formed the major fraction in mother plants (20.45%–21.86% and 16.17%–21.27%, respectively) and control seedlings (23.32%–24.95% and 18.95%–20.81%, respectively), while beta-Phellandrene was dominant in the selected putative mutant samples (2.34%–29.53%). Among sesquiterpenes, trans-Caryophyllene was detected only in the putative mutant samples (0.10%–30.18%). Grouping together of mother plants and control seedlings was seen in the cluster analysis, while the putative mutants grouped apart from them suggesting genetic diversity. Genetic distance between the mother plants and control seedlings ranged from 0.97 to 2.73, while between putative mutants, control seedlings, and mother plants, it ranged from 6.54 to 9.82. SSR-based characterisation of putative mutant seedlings showed that mutation caused variability in the treated population. This was evident from the high allelic richness ranging from 4 to 12 with a mean of 7 and a higher mean Shannon’s Information Index (1.50) of the putative mutant population.DiscussionThe study demonstrates that volatile profiling and molecular characterisation using SSR markers could be used as a tool to detect variation in a mutated population. In addition, volatile profiling can be used to validate putative mutants in polyembryonic mango genotypes where the seedlings of nucellar origin are similar to mother plants.

本研究通过γ射线照射多胚芒果基因型Nekkare，生成潜在突变体。对潜在突变体后代、对照种子和母本植物进行了评估，通过比较其主要挥发性化合物的组成和相对比例。采用顶空固相微萃取（HS SPME）法结合气相色谱-质谱联用（GC-MS MS）技术进行挥发性分析。此外，利用简单序列重复（SSR）标记对潜在突变体和对照种子进行表征，以确定研究样本中的遗传多样性。结果表明，单萜类化合物是所有研究样本中最丰富的挥发性化合物（含量范围为34.76%至91.41%），其中I-芳樟烯和顺式香茅烯在母本植物（分别为20.45%–21.86%和16.17%–21.27%）和对照种子（分别为23.32%–24.95%和18.95%–20.81%）中构成主要部分，而在选定的潜在突变体样本中，β-芳樟烯占主导地位（2.34%–29.53%）。在倍半萜类化合物中，仅检测到反式月桂烯存在于潜在突变体样本中（0.10%–30.18%）。聚类分析显示，母本植物和对照种子聚集在一起，而潜在突变体则与之分离，表明存在遗传多样性。母本植物与对照种子之间的遗传距离范围为0.97至2.73，而潜在突变体、对照种子和母本植物之间的遗传距离范围为6.54至9.82。基于SSR的潜在突变体种子表征显示，突变导致了处理群体中的变异。这从高达4至12的等位基因丰富度以及潜在突变群体较高的平均香农信息指数（1.50）中得以体现。讨论部分指出，挥发性分析及基于SSR标记的分子表征可作为检测突变群体中变异的工具。此外，挥发性分析可用于验证多胚芒果基因型中的潜在突变体，在这些基因型中，核源种子与母本植物相似。