Molecular Plant Breeding 2016, Vol.7, No.24, 1
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acid, lignoceric acid and ricinoleic acid (Table 3). However, their contents were pronounced difference in crude fat
and seeds. Ricinoleic acid was the greatest change among all fatty acid compositions of seed under different
development stage, from 6.70% to 86.80%, followed by linoleic acid (5.60%-31.30%) and palmitic acid
(1.20%-24.30%) (Table 3). Interestingly, several compositions were just found at initial seed filling phase and
significantly declined with seed maturity, e.g. mytistic acid, behenic acid and lignoceric acid were detected in
10-20 day-old seeds, suggesting that fatty acid composition of castor seed in the initial phases of seed formation
differed substantially form that of the mature seeds, which were similar to previous studies (Onemli, 2012; Baud
and Lepiniec, 2010).
Zeng et al. (2009) detected the fatty acid composition of castor seed collected from Hainan, China, and found that
the compositions included eight components, palmitic, stearic, oleic, linoleic, ricinoleic, pentadecanoic,
octadecenoic and octadecadienoic acid. Ramos et al. (1984) and Ramanjaneyulu et al. (2013) reported six major
ingredients of fatty acid compositions in castor bean from South India. Our previous studies reported eight
components in fatty acid composition of castor collected from Inner Mongolia (Huang et al., 2015a; Huang et al.,
2015b). All those researches indicated that fatty acid composition and content in different varieties were
significant different. Interestingly, in this study, we found that mostly major component in mature seed (30 d-60 d),
meanwhile, three other ingredients were firstly detected in earlier development stage of seed, including myristic,
behenic and lignoceric acid, which were absence in mature seed, which was also agree with (Takeuchi et al.,
1968). And our result suggested that fatty acid composition of castorbean was changed with development stage.
1.3 Correlation analysis and Cluster analysis of fatty acid and seed development time
In this study, the correlation analysis of different fatty acid composition and seed development time was employed
to investigate the content of composition under different stage (Table 4). The analysis results revealed significant
positive correlations of seed development time with stearic acid, oleic acid, linoleic acid, arachidonic acid and
ricinoleic acid, but showed negatively correlated with mytistic acid, behenic acid and lignoceric acid, suggesting
that the content of stearic acid, linoleic acid and ricinoleic acid increased during the development of seed and
indicating that synthesis of fatty acid composition were closely correlated with seed development. Oil content was
significantly positive relation with seed development time, stearic acid, oleic acid, arachidonic acid and ricinoleic
acid, while negatively correlated with mytistic acid, behenic acid and lignoceric acid. Palmitic acid was positive
correlation with linolenic acid, behenic acid and lignoceric acid. Linoleic acid showed positive correlation with all
others. In addition, a significant positive correlation was observed between oleic acid, arachidonic acid and stearic
acid.
The myristic, behenic and lignoceric acid contents were found to associate negatively with developing seed,
demonstrating that it was hard to detect those acids in mature seed. The content of linoleic, palmitic and oleic acid
decreased during castor seed development, while opposite result was found in Song et al. (2010). Additionally,
Rebetzke et al. (1996) revealed negative correlation between palmitic and oleic acid in soybean, which was
inconsistent with our present work. This different relationship may be due to species-specific factors.
Cluster analysis for fatty acid compositions and content is shown in Figure 2. Based on these characteristics, six
different developmental stages of seeds were classified into two groups. Group I included seed under 40-, 50- and
60-day-old. Ten to thirty-day-old seed were separately joined together. This grouping result reflected the fatty acid
composition of castorbean seed. Group I included mostly main fatty acid, which also found in other study (Bale et
al., 2013) and other crops (Guo et al., 2015; Choudhary et al., 2015). Group II mainly included trace amount of
myristic, behenic and lignoceric acid. The findings clearly suggested that fatty acid compositions could alter in the
seed development, in which associated with fatty acid metabolism related enzyme activity (Zhong-min et al.,
2011).
