Presently, selection of hybrid seedlings in coconut nurseries
relies on morphological markers, some of them being days taken for
germination, vigour of seedlings in terms of leaf production, higher
collar girth during a specific duration and petiole colour. The selection
of hybrids by petiole colour (Bourdeix, 1988) has limitations as
it is reliable only if progenitors homozygous for yellow, red or green
petiole are used. Furthermore, many of the varieties and hybrids are
phenotypically less distinct at early stages making morphological selection and evaluation more difficult. Identification of genuine
D
×
T (Dwarf
×
Tall) hybrids in the nursery stage is still more
difficult task if the female parent is a green dwarf in which case,
petiole colour is not useful for selection of hybrids. Though widely
adopted and practiced, purity assessments based on morphology is
often affected by environment, besides the higher requirement of
time and resources. Identification of molecular markers for distinguishing
plant-type character, therefore, is imperative for isolating
true-to-type high-yielding tall and hybrid lines in the early stage
of coconut breeding programmes which would be helpful in the
commercial hybrid seedling production activities in coconut. Differentiation
of dwarf, tall and hybrid types in the nursery based
on combined application of morphological and molecular markers would be expected to ensure quality of planting material in terms
of genetic purity.
In this study, we have described a technique of DNA pooling and
RAPD technique to identify markers linked to tall-type palm trait
in coconut. The methodology of pooling DNA for isolation of traitspecific
markers has been reported earlier in Chinese jujube (Peng
et al., 2001), Ponkan mandarin (JinPing et al., 2009) and betel vine
(Khadke et al., 2012) and this methodology proved to be effective
and practical in coconut too.
The fidelity of RAPD as a genetic marker technique has been
questioned because of the numerous technical disadvantages associated
with the RAPD technique. The reproducibility of RAPD is
affected by many factors: the quality of template DNA, the concentration
of primer and template, the different sources of DNA
polymerase, etc. The reproducibility and reliability of RAPD assays
can be significantly improved by the conversion of RAPD to SCAR
markers, by developing longer, and hence, more specific primers
from RAPD sequences. The linkage of the SCAR marker to talltype
palm trait in coconut was validated by screening the designed
primer pair in a range of tall and dwarf coconut accessions of different
geographical origins indicating the usefulness of the SCAR
makers for marker-assisted breeding.
In earlier studies, RAPD markers have been utilized for genetic
diversity studies of coconut accessions (Ashburner et al., 1997;
Upadhyay et al., 2004), but there are no reports of tagging of planttype
trait in coconut using molecular marker technology as in other
plant species such as Brassica rapa (Muangprom and Osborn, 2008),
Brassica napus (Foisset et al., 1995), Prunus (Manago and Bliss,
1998), wheat (Sourdille et al., 1998) and banana (Damasco et al.,
1996).
In conclusion, a marker related to tall-type plant trait has been
identified using RAPD markers. The SCAR primers designed using
this sequence variation was found to be specific for tall accessions
making the technique more stringent and specific when compared
with the RAPD marker. Studies of inheritance of plant-type character
in coconut has occupied a major place in coconut breeding
programmes as most of these programmes aim in developing a
D
×
T or T
×
D hybrids. The SCAR marker can be utilized to distinguish
selfed progenies in D × T crosses, as presented in this study.
Also, during selection of pure dwarf progenies in nurseries, the
SCAR marker would be of immense use in culling out of out-crossed
seedling progenies resultant of tall pollen contamination. Thus,
the SCAR marker for distinguishing tall and dwarf coconut accessions
would give headway in establishing further varietal identity,
achieving varietal purity within germplasm and ensuring the quality
of planting material in hybrid planting material production in
coconut.
ผลลัพธ์ (
จีนดั้งเดิม) 3:
[สำเนา]คัดลอก!
目前,選擇在椰子樹苗的混合托兒所
依靠形態標記,其中一些被天採取
發芽、活力的樹苗的葉的生產、高
領周長在一個具體時間和葉柄顏色。 甄選
的雜交葉柄顏色(由1988年)、布爾代也有其限制,
,才是可靠的工作純黃色,紅色或綠色
葉柄的使用。 此外,許多品種雜交,是
點較少在初期階段作出不同形態甄選和評價工作更困難。 查明真正
D
T(侏儒
高)雜交的幼兒園階段仍更
困難的任務如果女家長是一個綠色箭在這種情況 下,
葉柄顏色不十分有用的雜交的甄選。 雖然普遍
通過和實行基於形態,純度評估是
往往受影響的環境,除了較高的要求,
時間和資源。 身份查驗的分子標記為區分
廠-類型字符,因此,必須以隔離
真正到類別高產高樓和混合路線的早期階段
的椰子繁殖方案,將有助於
商業混合幼苗生產活動的椰子。 區分
的侏儒,高樓和混合類型的托兒所的
合並應用的形態和分子標記預期將會確保高質量的種植材料在
遺傳 純度.
在 這項研究,我們描述一個技術的DNA匯集和
中技術,確定標記與泰勒-類別Palm特性
在椰子。 的方法,匯集DNA traitspecific
標記已被隔離,在早些時候報道中國棗樹(彭
et al同上,2001)、ponkan國語(錦屏et al,2009年)和茇 葡萄
(khadke et al,2012年),這種方法被証明是有效
和實際的椰子 太.
中 的忠誠,作為一個基因標記技術已被
質疑的,因為許多技術缺點聯系
與中的技術。 再生性的,是
中受影響的許多因素的質素的模板:DNA,集中
的底漆和模板,不同來源的DNA
聚合酶等再生性和可靠性中測定
可以大大改善了的轉換中,傷痕
標記,以發展更長時間,因此,更具體底漆
從中序列。 的聯系的傷痕標記以talltype
Palm特性的椰子是審定,篩選的設計
底漆配對在一系列的高樓和矮椰子加入不同
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