196 – II.3. BRASSICA CROPS (BRASSICA SPP.)
parent, a finding at odds with the RFLP and chloroplast DNA investigations noted above.
However, the difference may be related to the limited Chinese genotypes that were
available to other researchers.
There has been much speculation in the literature as to the centre(s) of origin for
B. juncea. However, Prain (1898), Sinskaia (1928) and Vavilov (1949) all agree that
China, where the greatest divergence of forms occurs, is one centre of origin. In addition,
Vavilov (1949) also identified Afghanistan and adjoining regions as a second primary
centre. This observation was supported by Olsson (1960) and Mizushima and Tsunoda
(1967) as well as Tsunoda and Nishi (1968), who found wild forms growing on the
plateaus in Asia Minor and southern Iran. India and the Caucasus have also been put
forward as secondary centres (Hemingway, 1995; Figure 3.32). There is strong evidence
for China as a primary site. As noted in the B. rapa section above, B. juncea has a long
history in China. Leafy, vegetable forms of B. juncea mustard are also consumed in great
quantities in China and other Asian countries (Herklots, 1972; Nishi, 1980). The greatest
range in leaf types occur in Sichuan Province within the varieties of rugosa, japonica,
integrifolia and cernua. A root-forming type has also been selected and cultivated in
northern China with the variety names of napiformis and tumida (Nishi, 1980; Chen et al.,
2005).
The B. juncea from Afghanistan and Asia Minor is believed to have migrated south to
Pakistan and India where a secondary centre of origin was established (Figure 3.32).
The earliest direct reference to B. juncea is in the Indian Sanskrit literature about
1500 B.C., where it is mentioned as “Rajika” (Prakash and Hinata, 1980). The existence
of two primary centres in China and the Middle East-India is supported by the fact that
the Indian sub-continent and Chinese oilseed forms not only differ in morphological traits
(Sinskaia, 1928), but also chemically and in day-length requirements. The seed from
Indian B. juncea material contains mainly 3-butenyl glucosinolate and the crop is day
neutral, while the Chinese spring-sown oilseed forms contain only 2-propenyl (allyl)
glucosinolate and are long day requiring. The Chinese material also contains pure yellow
seeded strains which are absent in the Indian material. The Russian material displays
most of the same characteristics as the Chinese material and although it may also have
resulted from an independent interspecific cross, more likely it was carried into the
Russian Federation from China or Mongolia via the Northern Silk Road. Wu et al. (2009)
investigated the relationships among 95 B. juncea accessions originating from China,
France, India, Japan and Pakistan, using sequenced related amplified polymorphisms
(SRAPs). They found the Chinese vegetable phenotypes formed a highly diverse group
with the spring- and winter-sown oilseed forms split into two separate groupings.
The winter-sown accessions exhibited more genetic diversity than the spring-sown
accessions but less than the vegetable group. The SRAP markers did not provide a clear-
cut separation between the Indian/Pakistan and Chinese winter-sown mustards.
Srivastava et al. (2001), using AFLP markers, investigated the relatedness of oilseed
B. juncea cultivars from Australia (2 cultivars), Canada (2), China (2), Europe (6),
India (7) and Tibet (1). Their data separated the cultivars into an Indian/Chinese group
and a second cluster of the remaining ones. Their findings and that of Wu et al. (2009)
suggest a close relationship between the Chinese northern spring-sown oilseed cultivars
and the European mustards, while the winter-sown cultivars are closely associated with
the Indian form. The data from both Wu et al. (2009) and Qi, Zhang and Yang (2007)
support the contention of Song, Osborn and Williams (1988b) that the vegetable and
oilseed mustards had a polyphyletic origin and evolved separately.
