Table_1_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，生成了假定性突变体。对假定性突变后代、对照幼苗及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来进行分析。采用顶空固相微萃取（HS-SPME）方法结合气相色谱-质谱联用（GC-MS MS）进行挥发性分析。此外，利用简单序列重复（SSR）标记对假定性突变体和对照幼苗进行表征，以确定研究样本中的遗传多样性。结果显示，单萜类化合物在所有研究样本中最为丰富（含量范围在34.76%至91.41%之间），其中1-桉树脑和顺式香茅烯在母本植物（含量分别为20.45%–21.86%和16.17%–21.27%）及对照幼苗（含量分别为23.32%–24.95%和18.95%–20.81%）中占主要部分，而在选定的假定性突变样本中，β-桉树脑占主导地位（含量在2.34%–29.53%之间）。在倍半萜类化合物中，仅检测到反式胡椒烯存在于假定性突变样本中（含量在0.10%–30.18%之间）。聚类分析显示，母本植物和对照幼苗聚类在一起，而假定性突变体则与之分离，这表明存在遗传多样性。母本植物与对照幼苗之间的遗传距离在0.97至2.73之间，而假定性突变体、对照幼苗与母本植物之间的遗传距离在6.54至9.82之间。基于SSR的假定性突变幼苗表征显示，突变导致了处理人群中的变异。这从假定性突变群体的高等位基因丰富度（4至12个，平均值为7）以及较高的Shannon信息指数（平均值为1.50）中得以体现。讨论部分指出，挥发性分析及分子表征利用SSR标记可以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假定性突变体，在这些基因型中，核源幼苗与母本植物相似。