The volatile constituents of three different clones of durian (Durio zibethinus Murr.) were isolated by vacuum distillation with subsequent extraction of the distillates with dichloromethane. The concentrated extracts were analysed by capillary GC and GC-MS. A total of 63 constituents were identified, comprising 30 esters, 16 sulphurcontaining compounds, 5 ketones, 8 alcohols and 4 miscellaneous compounds. All three clones produced approximately the same proportions of esters and of ketones. The first-mentioned chemical class was quantitatively the most important among durian volatiles. There was much variation in the content of sulphur volatiles among the three clones. Identified among this chemical class were some uncommon plant volatiles such as cis-and trans-3,5-dimethyl-1,2,4-trithiolane and S-alkyl esters of alkylthiocarboxylic acids.

The volatile constituents of the fruits of Lansium domesticum Correa (duku and langsat) and Baccaurea motleyana (Muell. Arg.) Muell. Arg. (rambai) were isolated by vacuum distillation with subsequent extraction of the distillates with dichloromethane. The concentrated extracts were analysed by capillary GC and GC-MS. The volatile constituents of both duku and langsat fruits were dominated by sesquiterpene hydrocarbons, the most abundant of which was germacrene-D. (E)-Hex-Zenal was the major component of rambai fruit volatiles which also contained high levels of methyl 2-hydroxy-3-methylbutanoate, methyl 2-hydroxy-3-methylpentanoate and methyl 2-hydroxy-4-methylpentanoatc.

The responses of plants to recurrent stress may differ from their responses to a single stress event. In this study, we investigated whether clonal plants can remember past environments. Parental ramets of Glechoma longituba (Nakai) Kuprian were exposed to UV-B stress treatments either once or repeatedly (20 and 40 repetitions). Differences in DNA methylation levels and growth parameters among parents, offspring ramets and genets were analysed. Our results showed that UV-B stress reduced the DNA methylation level of parental ramets, and the reduction was enhanced by increasing the number of UV-B treatments. The epigenetic variation exhibited by recurrently stressed parents was maintained for a long time, but that of singly stressed parents was only short-term. Moreover, clonal plants responded to different UV-B stress treatments with different growth strategies. The one-time stress was a eustress that increased genet biomass by increasing offspring leaf allocation and defensive allocation in comparison to the older offspring. In contrast, recurring stress was a distress that reduced genet biomass, increased the biomass of storage stolons, and allocated more defensive substances to the younger ramets. This study demonstrated that the growth of offspring and genets was clearly affected by parental experience, and parental epigenetic memory and the transgenerational effect may play important roles in this effect.

Clonal plants in heterogeneous environments can benefit from their habitat selection behavior, which enables them to utilize patchily distributed resources efficiently. It has been shown that such behavior can be strongly influenced by their memories on past environmental interactions. Epigenetic variation such as DNA methylation was proposed to be one of the mechanisms involved in the memory. Here, we explored whether the experience with Ultraviolet B (UV-B) radiation triggers epigenetic memory and affects clonal plants’ foraging behavior in an UV-B heterogeneous environment. Parental ramets of Glechoma longituba were exposed to UV-B radiation for 15 days or not (controls), and their offspring ramets were allowed to choose light environment enriched with UV-B or not (the species is monopodial and can only choose one environment). Sizes and epigenetic profiles (based on methylation-sensitive amplification polymorphism analysis) of parental and offspring plants from different environments were also analyzed. Parental ramets that have been exposed to UV-B radiation were smaller than ramets from control environment and produced less and smaller offspring ramets. Offspring ramets were placed more often into the control light environment (88.46% ramets) than to the UV-B light environment (11.54% ramets) when parental ramets were exposed to UV-B radiation, which is a manifestation of “escape strategy.” Offspring of control parental ramets show similar preference to the two light environments. Parental ramets exposed to UV-B had lower levels of overall DNA methylation and had different epigenetic profiles than control parental ramets. The methylation of UV-B-stressed parental ramets was maintained among their offspring ramets, although the epigenetic differentiation was reduced after several asexual generations. The parental experience with the UV-B radiation strongly influenced foraging behavior. The memory on the previous environmental interaction enables clonal plants to better interact with a heterogeneous environment and the memory is at least partly based on heritable epigenetic variation.